Heated wiper blade for motor vehicles and the like

ABSTRACT

A heated wiper blade for motor vehicles includes an elongated flexible beam and a heating element extending along the beam. The heating element may be configured to provide increased heat at the central portion of the blade and at the opposite ends of the blade. The flexible beam may include curved end portions and a flat or reduced curvature central portion. The heating element is preferably covered and sealed off to prevent loss of heat energy.

CROSS REFERENCE TO RELATED APPLICATION AND CLAIM TO PRIORITY

The present application is a continuation application of commonlyassigned, copending U.S. application Ser. No. 13/177,382, filed Jul. 6,2011, entitled HEATED WIPER BLADE FOR MOTOR VEHICLES AND THE LIKE, whichis related to U.S. Provisional Patent Application No. 61/361,628, filedJul. 6, 2010, entitled IMPROVED HEATED WIPER BLADE FOR MOTOR VEHICLESAND THE LIKE, both of which are incorporated herein by reference, andclaims priority thereto under 35 U.S.C. §119.

BACKGROUND OF THE INVENTION

The present invention relates to windshield wiper blades for motorvehicles and the like, and in particular to an improved heated wiperblade and associated method.

Heated windshield wipers are generally known in the art, and includemany different forms and designs. Some such heated wiper blades heat thewiper frame, arm and blade, or a combination of these members, using aheating element or some other type of added assembly. While such wiperblades are somewhat effective, they are inconvenient to both themanufacturer and the end user. For example, they are either very costlyto manufacture, thereby resulting in a high cost product that is passedthrough to the consumer, or they are very complex to install, therebyeliminating many of the do-it-yourself consumers. Also, such priordesigns fail to consider that the wiper should work effectively with thewindshield defrosting system of the motor vehicle as a fully integratedfunctional unit. Without the windshield defroster system, the windshieldwill freeze up with the accumulated snow and ice, creating a hazardoussituation.

A unique frameless heated wiper assembly is disclosed in U.S. Pat. No.7,721,382, the entire contents of which are incorporated by reference.While such wiper assemblies are generally effective, certainimprovements to the same would be advantageous.

SUMMARY OF THE INVENTION

One aspect of the present invention is a heated wiper blade for motorvehicles and the like having certain improvements to the inventiondisclosed in U.S. Pat. No. 7,721,382, as disclosed in greater detailhereinafter.

Yet another aspect of the present invention is to provide an improvedheated wiper blade and associated method that is economical tomanufacture, efficient in use, and particularly well adapted for theproposed use.

These and other advantageous of the invention will be further understoodand appreciated by those skilled in the art by reference to thefollowing written specification, claims and appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a heating element of a heated wiper bladeaccording to one aspect of the present invention;

FIG. 2 is a schematic view of a heated wiper blade made of conductingmaterial;

FIG. 2A is a partially schematic view of a beam and heating elementaccording to another aspect of the present invention;

FIG. 2B is a partially schematic view of a beam and heating elementaccording to another aspect of the present invention;

FIG. 2C is a partially schematic view of a beam and heating elementaccording to another aspect of the present invention;

FIG. 3 is a partially fragmentary isometric view of a portion of a motorvehicle including a heated wiper blade assembly and system according tothe present invention;

FIG. 4 is a partially fragmentary, exploded isometric view of a heatedwiper blade according to one aspect of the present invention;

FIG. 5 is a partially fragmentary side elevational view of the heatedwiper assembly of FIG. 4;

FIG. 6 is a cross-sectional of the heated wiper blade of FIG. 5 takenalong the line 6-6;

FIG. 7 is a cross-sectional view of the heated wiper blade according toanother aspect of the present invention;

FIG. 8 is an exploded view of the heated wiper blade of FIG. 7;

FIG. 9 is a cross-sectional view of the heated wiper blade of FIG. 5taken along the line 9-9; FIG. 5;

FIG. 10 is a cross-sectional view of another version of the heated wiperblade of FIG. 9;

FIG. 11 is a side elevational view of a beam for heated wiperassemblies, wherein the beam has a flat center portion;

FIG. 12 is a plan view of the beam of FIG. 11;

FIG. 13 is an isometric view of a temperature sensing unit;

FIG. 14 is a partially schematic view of a first wiring harness;

FIG. 15 is a partially schematic view of a second wiring harness;

FIG. 16 is a partially schematic view of a third wiring harness.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal” and derivativesthereof shall relate to the invention as oriented in the attacheddrawing. However, it is to be understood that the invention may assumevarious alternative orientations and step sequences, except whereexpressly specified to the contrary. It is also to be understood thatthe specific devices and processes illustrated in the attached drawings,and described in the following specification, are simply exemplaryembodiments of the inventive concepts defined in the appended claims.Hence, specific dimensions and other physical characteristics relatingto the embodiments disclosed herein are not to be considered aslimiting, unless the claims expressly state otherwise.

The reference numeral 1 generally designates a heated wiper bladeembodying the present invention, which is schematically illustrated inFIG. 2. A heating element 2 is embedded in wiper blade 1 using a uniquepattern to achieve an improved distribution of heat and wipingperformance. More specifically, increased heat is provided in the center3 of the wiper blade 1 to compensate for wind. Also, increased heat isprovided at a section “W” (FIG. 2). Inner boundary 6 of W may be about0.5 inches from each end 4 of the blade 1 to compensate for the metalportion of the blade 1 not being in contact with the heating element 2,and because the heating element cannot be positioned all the way to theends of the beam. The illustrated heating element 2 has leads 5 disposedadjacent the center 3 of blade 1, which are connected with theelectrical power system of the associated motor vehicle.

Heater element 2 may comprise a Kapton or silicone etched foil adhesivebacked strip. Thermistor or PTC material on the foil strip facilitatesregulation of the temperature of the blade 1. Preferably, wiper blade 1is grounded, so that only the positive lead needs to be run under thehood of the vehicle. Electrical power to the wiper blade 1 is preferablyprovided only after the ignition switch of the vehicle has been turnedon. Airflow is sealed off on each side of the center 3 of the wiperblades 1 utilizing a sealant or other suitable material to preventcooling of the heating element 2. A temperature sensor 12 may beenclosed in metal casing, rather than being exposed to the open air. Theetched foil strip shown in FIG. 2 is a convenient way to configure theheating element 2.

A graphite or graphite impregnated squeegee and/or rubber backing on thewiper blade 1 can be configured to have electrical power applied to heatthe squeegee and/or backing. Using graphite would electrically heatand/or assist heat transfer to the wiper blade 1.

In beam-type wiper blades, there is a spring metal that is curved whichfollows the curve of the windshield. This metal can be substituted withcarbon (graphite) that can be powered to produce heat for the wiperblade 1. Also, all of the metal brackets on current wiper blades can bemade using graphite instead of metal. In other words, a non-metal bladecan be heated by the electrical power of the motor vehicle.

Heated wire and/or etched foil heating tape can be embedded or extrudedduring the manufacturing process into the wiper bow, wiper blade backingand/or squeegee. The bow may be composed of metal, plastic, fiberglassand/or graphite. The backing and squeegee may be composed of rubber,embedded graphite, other materials, and/or other heat conductingmaterials.

A sensing and control module can be made for emergency vehicles of thetype normally stored inside buildings that could be around 70° F. Inapplications such as this, the heated wiper blades 1 are preferably onand ready for use at all times. For example, if the air temperature is70° F., a normal heated blade may get too hot if full power is suppliedto the blade. Excessive power to the blades may cause the blades to gettoo hot, resulting in melting of rubber and/or plastic components. Thus,providing a module that reduces the electrical power supplied to theheating elements of the blades to ensure that the blades do not get toohot under such operating conditions is preferred for applications suchas this. The module includes a temperature sensor that senses the highertemperature of the storage area, and provides a reduced voltage to theheated wiper blade 1 at higher (e.g., 70° F.) temperatures. For example,most vehicles consume 14.6 volts when started, or approximately 12.6volts from the battery when the vehicle is not running. However, theheated wiper blade 1 may only require 10.0 volts for proper heat at 70°F. The control module may be configured to provide 11.0 volts if thetemperature is 30° F., 13.0 volts at 0° F., 13.0 volts, etc. Similarly,the controller may be configured to shut off all electrical power to theblades if the air temperature exceeds 80° F. or other predefinedtemperature. This provides a completely automatic system or mode thatallows the heated wiper blades to be left on at all times. PTC material,thermistor or thermostat, etc., can be utilized to accomplish thisfunction as well.

Reducing electrical power at increased temperatures can also beaccomplished to some extent by utilizing nickel 200 (referred to asPTC—Temperature Change with Resistance) material for the heating element2. As the ambient (air) temperature goes down, the resistance of theheating element wire or etched foil decreases and the current increases,increasing the wattage of the heated wiper blade 1, thereby producing ahigher temperature.

FIG. 1 illustrates another way of manufacturing and connecting power tothe heated wiper blades. By making some or all of the parts of the bladeassembly from a conducting material, such as graphite, supplyingelectrical power to such parts causes them to heat. In FIG. 1, centerbracket 13, beam 14 and squeegee 15 are made of a conducting material.FIG. 1 also shows schematically how these components could be connectedto the power source by leads 5 such that electricity flows through thecomponents. It will be understood that the leads 5 may compriseinsulated wire that is routed along the blade to bracket 13, and furtherrouted along a wiper arms 10 (FIG. 3).

As discussed in more detail below, a wiring harness may be used toelectrically connect the heated wiper blade to the electrical powersource. The wiring harness can be made in various ways, includingmolded, different wiring devices, crimps, connectors, inline splices,twist connectors, waterproof connectors, plug-in connectors, anddifferent wire lengths, sizes and colors. Different vehicles may needdifferent wiring harnesses to accommodate various heated wiper blades.In some vehicle, like fire trucks, UPS trucks, bread trucks, etc., thewipers extend down from the bulkhead of the vehicle. This would requirea different wiring harness with waterproof, ultraviolet-resistant wiresand connectors.

All wires coming from the heated wiper blades are preferably flexible,ultraviolet-resistant (sun), oil-resistant, and be capable of carryingat least five amps of current. All harnesses going to the heated wiperblades also require a fuse.

A temperature sensor may also be included with the wiring harness. Thewiring harness may also include a module and/or connectors that connectto the computer or processor associated with the vehicle, so that if thewires should fail or become disconnected, a warning light or signalwould alert the driver. Also, fuse holders, inline fuses, on/offswitches, etc., could be included with the harness.

With further reference to FIG. 3, the heated wiper blades 1 are mountedto existing arms 10 of a vehicle windshield wiper system. The heatingelements 2 of blades 1 may be connected to wiring 22 utilizingdisconnectable connectors 25. Alternately, the leads 5 of heatingelement 2 may be connected directly to wires 22. A manual switch 21 maybe disposed in the vehicle interior for operation by a user. Switch 21is connected to module 17 by a wire 23, and module 17 is connected tovehicle battery 16 by wire 19 and to vehicle ground by a wire 19 a. Atemperature sensor 18 may be mounted directly behind a vehicle grill 28such that the temperature sensor 18 is exposed to ambient air duringvehicle operation. As discussed in more detail below, temperature sensor18 may comprise a thermal mass to prevent abrupt changes in the sensedtemperature. Temperature sensor 18 is operably connected to module 17 bywires 20. Different control arrangements and wiring harnesses arediscussed in more detail below.

Referring again to FIG. 2, heating element 2 includes first and secondend portions 7 a and 7 b, respectively, each having a length “W”. Ingeneral, if the overall length A of heating element 2 and blade 1 is 18inches, B is preferably about 7.0 inches. If A is 21 inches, B ispreferably about 8.5 inches. If A is 23 inches, B is preferably about9.5 inches, and if A is 27 inches, B is preferably about 11.5 inches.Heating element 2 also includes a central portion 8 having a length “C”,and first and second intermediate portions 9 a and 9 b, respectively,each having a length “B”.

In the example illustrated in FIG. 2, the heating element 2 comprises afilm 31 having a conductive element 30 disposed on the film 31.Connectors 25 may be disposed at the ends of leads 5 to provide forconnecting and disconnecting leads 5 from wires 22 (see also FIG. 3)that operably connect the heating element 2 to battery 16 of thevehicle. Alternately, wiring 22 may be permanently connected to leads 5,and a suitable releasable connector may be provided at module 17. Theconductor 30 may comprise etched foil comprising nichrome or othersuitable conductive material. Conductor 30 is preferably comprisesnickel 200 or other material having an electrical resistance that isgreater at higher temperatures, and lower at lower temperatures. Ingeneral, such conductive materials are referred to herein as “PositiveTemperature Coefficient” (PTC) materials. Use of a PTC conductor 30provides for reduced heat production by the heating element 30 at higherambient temperatures to thereby prevent overheating and damage to theblade assembly that could otherwise occur. Although the resistance ofconductor 30 may vary depending upon the needs of a particularapplication, testing of a heated wiper blade 1 including a nickel 200conductor 30 shows that conductor 30 may be configured to provide 1.4Amps at 0° F., 1.74 Amps at 40° F., and 1.64 Amps at room temperature(approximately 72° F.). Thus, the use of a PTC material provides moreamps (heat) at lower temperatures and less amps (heat) at highertemperatures even without a separate controller.

The film 31 may comprise a Kapton style ribbon/tape, a PET film, a heavyfilm, or other suitable film material. Furthermore, heating element 2may comprise a silicone rubber sheet 31 having a conductor 30 disposedon the outside of the sheet 31, or the conductor 30 may be embedded inthe silicone rubber sheet 31. It will be understood that the conductor30 of FIG. 2 would appear in dashed lines if conductor 30 were imbeddedin a silicone rubber sheet 31.

Still further, conductor 30 may comprise a wire heating element made ofnichrome or nickel 200 or other suitable materials having an insulatingcover or sheath comprising Teflon, PVC, or other suitable material. Ingeneral, Teflon is preferred due to its higher temperature capabilities.An example of a wire having a conductor 30 with an insulating outercover or sheath is shown in FIG. 5 a of U.S. Pat. No. 7,721,382

Conductor 30 may define a series of longitudinally extending portions 32and transversely extending portions 33. The longitudinally extendingportions 32 may have a reduced length at end portions 7 a and 7 bcorresponding to the dimension “W”, and also along the central portion 8having a dimension “C”. This provides a higher heat output in theregions 7 a and 7 b and c, relative to the intermediate portions 9 a and9 b. The conductor 30 may provide a heat output that can be expressed interms of heat energy per unit length of heating element 2. The closerspacing of transverse portions 33 of conductor 30 provides forsubstantially increased heat output per unit length at the end portions7 a and 7 b, and also at the central portion C of heating element 2.Because the conductor 30 may not extend all the way to the opposite endsof beam 14, the additional heat provided in end portions 7 a and 7 bcompensates for this and reduces build up of snow and ice at theopposite ends 4 of the wiper blade. Similarly, the increased heatprovided by the closer spacing of longitudinal portions 32 of conductor30 at the central portion C compensates for additional heat loss thatmay occur due to positioning of conductor 30 away from beam 14 atbracket 13. It will be understood that heating element 2 may provideincreased heat output per unit length at only the center portion C, orat one or both of the end portions 7 a and 7 b, or at both the centralportion C and the opposite end portions 7 a and 7 b.

With further reference to FIG. 2A, heating element 2 may comprise anelongated wire 35 that is disposed directly on an upper surface 36 ofbeam 14. Suitable retainers, adhesives, or clips 37 may be utilized tosecure the wire 35 to the beam 14. The wire 35 of heating element 2 maycomprise an elongated wire made of nickel 200, nichrome or othersuitable conductive material that is encased in a sheath of insulatingmaterial such as PVC or Teflon. In general, wire 35 has an electricalresistance in the range of about 1-16 ohms per meter, depending upon thetotal length “A” of the beam 14, and the other requirements for aparticular application.

With further reference to FIG. 2B, heating element 2 may also comprisewires 40 that are secured to upper surface 36 of beam 14 utilizing clips37, adhesive, or the like in a manner that is substantially similar tothe arrangement discussed above in connection with FIG. 2A. Wire 40 maycomprise an inner conductor made of nickel 200, nichrome, or othersuitable material that is covered by an insulating material such asTeflon, PVC, or the like. In general, wire 40 may be substantially thesame as wire 35 discussed above in connection with FIG. 2A. Wire 40 mayinclude portions 41 a, 41 b, and 42 providing increased heat output perunit length of the blade at opposite end portions 7 a, 7 b, and atcentral portion 8. Portions 41 a, 41 b, and 42 may comprise a sine waveor the like providing increased heat per unit length at the oppositeends and central portions of the heating element 2 of FIG. 2B.

With reference to FIG. 2C, a heating element 2C corresponding to anotheraspect of the present invention includes a wire 45 that is secureddirectly to upper surface 36 of beam 14 utilizing clips 37 or othersuitable connectors such as adhesives, or the like. Wire 45 may besubstantially the same as wires 35 and 40 discussed above in connectionwith FIGS. 2A and 2B, respectively. Wire 45 may form one or moreadditional loops 46 providing additional heat output at end portions 7 aand 7 b, and one or more additional loops 47 at central portion 8. Itwill be understood that a single loop 47 may be utilized with a U-bendend 38 (FIG. 2A), or wavy portions 41 a and 41 b (FIG. 2B). Similarly,the additional loops 46 (FIG. 2C) may be utilized in conjunction with awire having a straight central portion (FIG. 2A), or a wavy centralportion 42 (FIG. 2B). Also, any combination of the features shown inFIGS. 2, 2A, 2B, and 2C may be utilized to provide additional heat atonly the opposite ends 7 a and 7 b, only the central portion 8, or atthe end portions 7 a and 7 b and central portion 8.

With further reference to FIGS. 4 and 5, heated wiper blade 1 maycomprise a beam-type wiper blade having beam 14 and squeegee 15 that isconnected to beam 14. Beam 14 may include tabs 27 (see also FIG. 8) thatextend around opposite edges 29 a of squeegee 15 to thereby secure beam14 to squeegee 15. Other suitable connecting arrangements may also beutilized. Heated wiper assembly 1 also includes elongated covers 50 aand 50 b, a central cover 51, and a bracket 13 that is utilized tointerconnect the heat wiper blade 1 with an existing arm 10 of a vehiclewiper system. The beam 14, squeegee 15, covers 50 a, 50 b, and 51, aswell as bracket 13 may be substantially similar to commerciallyavailable beam type wiper blades. The covers 50 a and 50 b and 51, aswell as squeegee 15 are preferably made of materials that can withstand200-300° F. Similarly, adhesives, sealants, filler material, and thelike also preferably comprise materials that can withstand temperaturesof 200-300° F. In general, beam-type blades made by variousmanufacturers are readily available from various retail outlets. Thecovers, beam, and squeegee will therefore not be described in detailherein, except as necessary to describe the differences between theheated wiper blade 1 of the present application and commerciallyavailable non-heated beam type wiper blades.

Wiper assembly 1 (FIGS. 4 and 5) further includes heating element 2which may be in direct contact with upper surface 36 of beam 14 asdescribed above in connection with FIGS. 2, 2A, 2B, and 2C. Heatingelement 2 may comprise any one of the heating elements described in moredetail above in connection with FIG. 2, 2A, 2B, or 2C. As discussedabove, heating element 2 may be connected to a module 17 utilizingwiring 22. It will be understood that some of the components of thewiring harness are not shown in FIGS. 4 and 5. When assembled, innerends 52 a and 52 b of covers 50 a and 50 b respectively, are received inopenings 53 a and 53 b of cover 51. Wiring 22 may pass through opening53 a or opening 53 b, and a heat resistant sealant 54 (FIG. 5) may beprovided at openings 53 a and 53 b to provide an airtight seal betweencovers 50 a, 50 b, and cover 51. The heat resistant sealant 54 is alsoutilized to provide an airtight seal around wires 22 where they enteropening 53 a or 53 b.

With further reference to FIG. 6, a cavity 55 (see also FIG. 7) isformed by covers 50 a and 50 b. Heating element 2 is disposed in cavity55. Sealant 54 is utilized at edges 56 of cover 50 b to provide anairtight connection between cover 50 b, squeegee 15 and/or beam 14 suchthat cavity 55 is substantially airtight. Edge portions 56 of covers 50a and 50 b preferably include a tapered wedge-like surface 49 and a pairof inwardly facing longitudinal grooves 48 (See also FIG. 8). Duringassembly, beam 14 is pushed into engagement with covers 50 a and 50 bsuch that opposite edges 24 of beam 14 engage tapered edges 49, and thensnap into inwardly-facing grooves 48 (See also FIG. 8). A sealant 54 orthe like is preferably disposed around the opposite side edges ofheating element 2 and/or beam 14 and/or squeegee 15 to provide anairtight seal as discussed below, sealant 52 may be disposed insidecovers 50 a, 50 b, and 51 (FIGS. 4 and 5). Covers 50 a and 50 b, beam14, squeegee 15, heating element 2, and sealant 54 are preferably madeof materials that are selected to withstand 200-300° F. Sealant 54 ispreferably a high temperature sealant that does not degrade at thehigher temperatures generated by heating element 2. The squeegee 15 isadhesively adhered, or otherwise mechanically connected, directly tobeam 14 whereby upper surface 26 of squeegee 15 is in direct contactwith lower surface 34 of beam 14 to thereby facilitate heat transfertherebetween. This also facilitates faster, more efficient assembly.

Cavity 55 may comprise an empty cavity as shown in FIG. 7, or sealant 52or a filler material 57 (FIG. 6) may be injected into cavity 55. Fillermaterial 57 may comprise a flexible sealant material that is capable ofwithstanding the higher temperatures resulting from heating element 2.In general, filler material 57 may be injected into cavity 55 in aliquid or highly viscous form, and the filler material 57 then cures toform a solid mass. Alternately, covers 50 a and 50 b may comprise arelatively hard outer layer and filler material 57 that defines an innercore formed at the time the covers 50 a and 50 b are fabricated. Theshell and core 57 may be formed utilizing a molding process or the like.The filler material 57 is significantly softer than the outer layer ofthe shell. During assembly, the covers 50 a and 50 b (with fillermaterial 57) are snapped onto the beam as described above. The fillermaterial 57 pushes down on the heating element 2 and causes the heatingelement to contact upper surface 36 of beam 14, thereby ensuring thatheat from heating element 2 is transferred into beam 14. Filler material57 also insulates the upper side of the wiper blade to prevent heatloss. The outer shell and the core filler material 57 may compriserubber having significantly different hardnesses, or the outer shell andthe core may comprise different materials. For example, the shell couldcomprise a relatively hard plastic, and the core could comprise anelastomeric rubber. Also the outer shell is preferably very smooth toprevent excessive buildup of snow and ice on the outside of wiperblades. Filler material 57 provides insulating properties such that moreof the heat from heating element 2 is transferred to the beam 14 and tosqueegee 15.

With reference to FIG. 9, bracket 13 may have a generally U-shaped crosssection with a lower flange or sidewall 59 and upwardly extendingflanges 58 a and 58 b. Lower flange 59 may be spaced apart from theupper surface 36 of beam 14 to form a gap 63. However, the gap 63 may betoo small to allow heating element 2 to be positioned therein betweenlower flange 59 and beam 14. Thus, heating element 2 may be disposed indirect contact with the upper surface 43 of lower flange 59 of bracket13. Gap 63 may be filled with filler material 57 to thereby provideincreased heat transfer from flange 59 to squeegee 15 adjacent bracket13.

With further reference to FIG. 10, heating element 2 may be disposedbetween lower flange or wall 61 of bracket 13 a and beam 14 if amodified bracket 13 a (see also FIG. 11) permit this configuration.

Bracket 13 a comprises a pair of generally upright side flanges 58 and58 b that are interconnected by an internal web or sidewall 61 or thelike to form a gap 62 that is large enough to receive heating element 2.Modified bracket 13 a permits heating element 2 to be disposed in directcontact with upper surface 36 of beam 14 where beam 14 extends throughor adjacent bracket 13 to thereby facilitate heat transfer from heatingelement 2 to beam 14 or 14 a and to squeegee 15 (see also FIG. 11).

With further reference to FIGS. 11 and 12, the beam may comprise a beam14 a having a substantially flat central portion 64, and curved outerportions 65 a and 65 b. In general, conventional beams 14 as shown inFIG. 4 have a uniform radius of curvature. This can tend to cause a gapbetween squeegee 15 and the windshield when the squeegee 13 is slidingover a portion of the windshield having less curvature. The straight orflat central portion 64 of beam 14 a ensures that the central portion ofsqueegee 15 stays in contact with the windshield surface. Also, straightor flat portion 64 reduces flexing of beam 14 a in operation, therebyreducing the tendency for heating element 2 to flex and break if heatingelement 2 is made from a material that cannot withstand repeatedflexing. In general, the overall nominal length “A” of heating element 2may be 18 inches, 21 inches, 23 inches, or 27 inches. The beam 14 istypically about one inch longer than heating element 2. The dimension“D” of flat central portion 64 of beam 14 a is preferably about 3-10inches (depending in part, on the dimension “A”, and curvature of thewindshield). In a preferred embodiment, the dimension “D” is about 4.5inches. However, it will be apparent that the precise dimension of flatcentral portion 64 is not necessarily critical in all applications.

Beams 14 and 14 a may be formed from flat strips of metal by stamping orother such suitable process. In general, the curved outer portions 65 aand 65 b of beam 14 a have a radius of curvature that is similar to beam14 (see also FIG. 4). The flat central portion 64 can be created fromflat metal stock by curving only end portions 65 a and 65 b during thestamping or other forming process.

Beams 14 and 14 a may be made from spring steel or other suitable metal.Alternately, beams 14 and 14 a may be formed from graphite, fiber glass,or a suitable polymer material. Furthermore, as noted above inconnection with FIG. 1, the beams 14 and 14 a may be made from aconductive material such that the beam 14 or 14 a itself acts as aheating element as described above in connection with FIG. 1. If thebeam 14 or 14 a is used as a heating element, a separate heating element2 is not required. Referring again to FIG. 4, other components of wiperblade assembly 1 such as the covers 50 a, 50 b, 51, and bracket 13 mayalso be made of a conductive material and operably interconnected withan electrical power source whereby these components also provide aheating function. In general, these components may be made of a metalconductive material or they may comprise a conductive plastic material.Conductive plastic material may comprise a plastic resin that has beenembedded with carbon powder or fiber to reduce the electricalresistivity of the plastic material. Plastic that has been formulatedwith stainless steel fiber, inherently dissipative polymer, or othersuch materials may also be utilized.

Beams 14 and 14 a may comprise an extruded polymer material, andconductor 30 may comprise an etched foil heating tape that is imbeddedor extruded into the beam 14 or 14 a. Conductors 30 may be extruded intothe beam 14 or 14 a. The spring beam may also comprise a carbon fibermaterial with conductor 30 extruded therein. The conductor 30 maycomprise a nickel 200 material, nichrome, or other suitable resistancematerial. Leads 5 interconnect conductors 30 with the other wiring inthe system. Leads 5 may protrude transversely from flat center portion64, or from opposite ends 4 a of beam 14 a.

Heated wiper blade 1 may comprise a beam-type wiper having a pair ofspring steel spines that connect to an elongated blade as shown in U.S.Pat. No. 7,721,382. The beam 14 may comprise a slotted elastic member asdisclosed in U.S. Patent Publication No. 2006/0026786, the entirecontents of which are hereby incorporated by reference. If the squeegeehas an upper surface that is above the upper surface of the beam orbeams (i.e. the beams are received in slots on opposite sides of thesqueegee), the heating element may be secured directly to the uppersurface of the squeegee utilizing adhesive, adhesive sealant, or thelike to ensure that heat from element 2 is transferred into thesqueegee.

With further reference to FIG. 13, temperature sensor 18 may comprise ablock 66 that is made of aluminum or other material having significantthermal energy storage capabilities. A hole or bore 67 is formed inblock 66, and a sensor element 68 is positioned in the bore 67 withwires 20 extending out of bore 67. Sealant 69 may be disposed in bore 67to provide a watertight seal around wires 20 and to retain sensorelement 68 in bore 67. If bore 67 extends all the way through block 66to form an open end 70, the open end 70 may also be filled with sealant69. Block 66 has a length X, a height Y, and a width Z. In general, thedimensions X, Y, and Z are chosen to insure that block 66 has sufficientthermal mass to prevent rapid temperature fluctuations of sensor element68. If the block 66 is made of aluminum, the length X may be about 1.5inches, and the height and width may be about 1 inch. Block 66 may bevarious shapes, including cylindrical, or other suitable shapes.

With reference to FIG. 14, a wiring harness 75 includes a battery 16, amodule 17, a temperature sensor 18 and connectors 25 a that releasablyinterconnect wiring 22 with leads 5 of heating elements 2 of heatedwiper blades 1. The electrical connectors 25 a may be positionedadjacent an end of arm 10 (see also FIG. 3). If the heated wiper bladeassemblies 1 are retrofitted to a vehicle, the module 17 temperaturesensor 18, and wiring 19, 22, and 23 may be installed in a vehicle, andconnectors 25 a may be utilized to releasably interconnect harness 75with heated wipers 1. If one of the heated wipers 1 requiresreplacement, it can be quickly and easily disconnected and replaced bydisconnecting a connector 25 a from the wiper blade being replaced,followed by interconnecting of connectors 25 a to the replacement blade1. In this way, once a vehicle has been retrofitted with the wipersystem, only the blade portion of the system needs to be replaced in theevent one of the heated blades 1 does not function properly.Alternately, a single connector 25 b and wire 22 b may be utilized tointerconnect wiring 22 with module 17. Connectors 25 a and/or 25 b arepreferably waterproof, 7 amp rated connectors having a very smallexternal size to reduce the visual effects of connector 25 a.Furthermore, if connector 25 b is very small, a hole in seal 76 (FIG. 3)can be formed, and connector 25 b can be passed through the hole. Ifrequired, sealant can be applied around the hole through seal 76. Thisreduces disruption of the seal around the vehicle hood.

A wiring harness 85 is similar to the wiring harness 75 of FIG. 14,further includes a connector 81 that may be utilized to interconnect thewiring harness to a vehicle fuse box. Alternately, a fuse 79 and fuseclip 80 may be utilized. The portions of wiring harnesses 75 and 85 thatare subject to flexing during use (i.e., the portions directly adjacentarms 10) are preferably made of a flexible wire that retains itsflexibility to at least −40° C. and more preferably retains itsflexibility to −60° C.

All of the connectors, wire splices, butt splices, and other componentsof the wiring harness are preferably moisture and water proof.Furthermore, all of the wire and connectors preferably meets automotivespecification such as TXL wire for portions of the wire that aredisposed in the engine compartment below the hood of the vehicle. Thewires going to the wiper blades 1 are preferably about 0.125 inches indiameter, and not less than 40 inches long, flexible, remaining flexibleto −65° F. As discussed above, the wires can be connected at the wiperblades 1, or under the hood of a vehicle. If the connectors are locatedunder the hood there is less chance of damage to the connectors from carwashes, wind, or the like. Also, as discussed above, the wire running tothe wiper blades 1 would be replaced with the wipers if an under hoodconnection is utilized. However, providing a connector at the wipergenerally provides for a lower cost wiper blade, and facilitatereplacement of in general, the system is configured to provide power tothe heated wiper blades 1 only if the vehicle ignition switch is on.Furthermore, the electrical system is grounded on the wiper arms 10,such that only a positive lead wire needs to be run under the hood of avehicle.

Module 17 may be configured to control the amount of electrical currentsupplied to heating elements 2 based on an ambient temperature sensed bytemperature sensor 18. Module 17 is configured in part, to account forthe material utilized to make the heating element 2. With reference toFIG. 16, module 17 may comprise sensors 18 a and 18 b. First sensor 18Acloses at approximately 0° F., and the sensor 18B closes atapproximately 40° F. The 40° sensor 18B has a dropping resister 100 thatreduces the voltage to approximately 10.6 volts from the 13.6 voltsprovided by a vehicles alternator during operation. Thus, the circuitcauses less voltage and heat at the blade when the temperature exceeds0° F. Although the 10.6 volt provides good operation in the temperaturerange of 0° F. to 40° F., additional heat is required when the operatingconditions are below about 0° F. When the ambient temperature is 0° F.or lower, the second sensor 18B bypasses the dropping resister 100whereby the heating element 2 of the wiper receives 13.6 volts. When13.6 volts is supplied to the heating element 2, the wiper bladeassembly 1 can be operated at temperatures between about −40° F. and 0°F., while preventing excessive heat (and attending damage) at operatingtemperatures from about 0° F. to about 40° F.

Module 17 may alternately comprise a Pulse Width Modulator (PWM) that issupplied with the vehicle at the time it's manufactured, or retrofittedto a vehicle. PWM may also comprise an aftermarket unit that isretrofitted to a vehicle, and may be used with our without PTCsensor/heating element, or other sensing means. Furthermore, a vehiclemay include a temperature sensor at the time it is manufactured. If thevehicle includes a PWM and a temperature sensor, module 17 can beconfigured to control voltage to heating element 2 to account forambient operating conditions. For example, the PWM may be configured toprovide electrical current to heating element 2 when the ambienttemperature is 40° F. or lower, and the electrical current may besupplied to the heating element 2 until a temperature inside the bladeas sensed by a temperature sensor exceeds about 150° F., at which pointthe PWM provides reduced current to prevent overheating of the heatingelement 2 and other components. As the temperature of the blade drops,the PWM provides less current (fewer pulses) until the temperature staysat approximately 150° F. even if the ambient temperature is −40° F.

If the heating element 2 does not include a positive thermal coefficientheating element, module 17 may include a voltage regulator. For example,module 17 may be configured to provide 8 to 10 volts to the heatingelement 2 when the ambient temperature is 40° F. As temperatures dropbelow 40° F., the module 17 is configured to regulate the voltage up to13.6 volts.

If a PTC conductor 30 is used, the resistance of the PTC conductor 30 isselected such that at an ambient temperature of 40° F. and 8 to 10volts, the blades do not exceed a predetermined maximum temperature, butrather stay at approximately 125-150° F. The proper resistance level forthe heating element 2 can be determined by testing different conductors(ohms/meter), until the proper resistance level is found to provide atemperature at the exterior of the blade of approximately 125-150° F.when the ambient temperature is −40° F. The specific resistance level ofthe conductor 30 will generally depend on the configuration of thevarious components such as the beam 14, covers 50 a and 50 b, as well asthe presence or absence of filler material 57 (FIG. 6). As discussedabove, in general conductor 30 will have a resistance in the range ofapproximately 1-16 ohms per meter if conductor 30 comprises a wirehaving a conductive element made from PTC material such as nickel 200 orother conductive material. and an insulating sheath made of Teflon, PVC,or the like. At temperatures below 40° F., the coefficient of electricalresistance of the conductor 30 is reduced if a PTC material is used,thereby providing increased heat from the conductor 30 such that theexterior surfaces of the wiper blades 1 stays at approximately the sametemperature without requiring a separate controller and temperaturesensor.

In the foregoing description, it will be readily appreciated by thoseskilled in the art that modifications may be made to the inventionwithout departing from the concepts disclosed herein. Such modificationsare to be considered as included in the following claims, unless theseclaims by their language expressly state otherwise.

The invention claimed is:
 1. A frameless heated wiper blade assembly forvehicle windshields, comprising: at least one elongated curved beamcomprising a flexible material suitable for conforming to a curvedwindshield, the curved beam defining oppositely facing upper and lowersurfaces, a central portion, first and second opposite ends, first andsecond opposite end portions that are directly adjacent the first andsecond opposite ends, respectively, a first intermediate portionextending between the first opposite end portion and the central portionand a second intermediate portion extending between the central portionand the second end portion; an elongated flexible squeegee attached tothe elongated curved beam; a bracket connected to the central portion ofthe elongated curved beam, wherein the bracket is configured toreleasably connect the heated wiper blade assembly to an arm of thevehicle windshield wiper system; an electrical resistance heatercomprising an elongated electrical conductor that produces heat whenelectrical current is passed through the electrical conductor, whereinthe electrical resistance heater is disposed along an outer periphery ofthe elongated curved beam and directly adjacent the upper surface of theelongated curved beam; and a cover extending over portions of theelectrical resistance heater that are directly adjacent the first andsecond opposite ends and the first and second intermediate portions ofthe beam to thereby prevent direct exposure of the electrical resistanceheater to air moving adjacent a vehicle in use.
 2. The frameless heatedwiper blade assembly of claim 1, wherein the electrical conductordefines an electrical resistance that varies with changes in temperaturewhereby the electrical resistance heater provides significantly moreheat energy at lower temperatures.
 3. The frameless heated wiper bladeassembly of claim 2, wherein the electrical resistance heater comprisesnickel
 200. 4. The frameless heated wiper blade assembly of claim 3,wherein the electrical resistance heater comprises an elongated wirethat is encased in a sheath of electrically insulative material, andwherein the elongated wire comprises a pair of leads adjacent thecentral portion of the elongated beam, and at least two elongated loopsextending in opposite directions away from the leads, and wherein theelongated loops include at least two strands of wire that extendgenerally side-by-side in contact with the upper surface of the beam. 5.The frameless heated wiper blade assembly of claim 1, wherein: theelongated beam defines a longitudinal length of the beam; and theelectrical conductor comprises a plurality of transverse portions thatextend transverse relative to the longitudinal length.
 6. The framelessheated wiper blade assembly of claim 5, wherein: the transverse portionsare substantially linear, and wherein the electrical conductor includesa plurality of substantially linear longitudinal portions extendinggenerally parallel to the longitudinal length and interconnecting thetransverse portions.
 7. The frameless heated wiper blade assembly ofclaim 6, wherein: adjacent transverse portions define distancestherebetween, and wherein the distances are smaller adjacent the firstand second opposite end portions of the beam than at the first andsecond intermediate portions of the beam.
 8. A frameless heated wiperblade assembly for vehicle windshields, comprising: at least oneelongated curved beam comprising a flexible material suitable forconforming to a curved windshield, the curved beam defining oppositelyfacing upper and lower surfaces, a central portion, first and secondopposite ends, first and second opposite end portions that are directlyadjacent the first and second opposite ends, respectively, a firstintermediate portion extending between the first opposite end portionand the central portion and a second intermediate portion extendingbetween the central portion and the second end portion; an elongatedflexible squeegee attached to the elongated curved beam; a bracketconnected to the central portion of the elongated curved beam, whereinthe bracket is configured to releasably connect the heated wiper bladeassembly to an arm of vehicle windshield wiper system; an electricalresistance heater comprising an elongated electrical conductor thatproduces heat when electrical current is passed through the electricalconductor, wherein the electrical resistance heater is disposed along anouter periphery of the elongated curved beam and directly adjacent theupper surface of the elongated curved beam; and a cover extending overportions of the electrical resistance heater that are directly adjacentthe first and second opposite ends and the first and second intermediateportions of the beam, wherein the electrical resistance heater isdisposed in an elongated cavity defined in part by an inner surface ofthe cover, and thereby prevents direct exposure of the electricalresistance heater to air moving adjacent a vehicle in use.
 9. Theframeless heated wiper blade assembly of claim 8, wherein: theelectrical resistance heater comprises a thin flexible film, and theconductor comprises a foil disposed on a side face of the film.
 10. Theframeless heated wiper blade assembly of claim 8, wherein: the elongatedcurved beam includes a generally linear portion at a center of theelongated beam and first and second elongated curved portions extendingoutwardly away from the linear portion in opposite directions.
 11. Theframeless heated wiper blade assembly of claim 10, wherein the beam ismade from metal having a substantially uniform thickness and width. 12.The frameless heated wiper blade assembly of claim 8, wherein: thecentral portion defines a center of the elongated beam; and wherein: thebracket defines a lower surface that is spaced apart from the uppersurface of the beam to define a gap therebetween, and wherein theelectrical resistance heater extends through the gap.
 13. The framelessheated wiper blade assembly of claim 8, wherein the cavity defined inpart by an inner surface of the cover is substantially filled with amaterial that encases the electrical resistance heater.
 14. Theframeless heated wiper blade assembly of claim 8, wherein the cavity issubstantially empty.
 15. The frameless heated wiper blade assembly ofclaim 8, wherein: the elongated beam defines elongated opposite sideedges; the cover is generally U-shaped in cross section with flexibleside walls, the cover and including a pair of inwardly facing groovesextending along edges of the cover, the cover further including taperededge surfaces adjacent the grooves whereby the cover can be snapped ontothe beam by pushing the cover onto the beam until the opposite edges ofbeam are received in the grooves of the cover.
 16. The frameless wiperblade assembly of claim 8, wherein: the central portion of the beam islinear.
 17. The frameless wiper blade assembly of claim 8, wherein: theheating element comprises a positive temperature coefficient materialthat generates a first heat energy if the heating element is at a firsttemperature, and generates a second heat energy that is significantlyless than the first heat energy if the heating element is at a secondtemperature that is significantly greater than the first temperature.18. The frameless heated wiper blade assembly for vehicles of claim 8,wherein the cover member comprises an outer layer and an inner core,wherein the outer layer is significantly harder than the inner core, andwherein the inner core pushes the electrical heating element intocontact with the upper surface of the beam.
 19. The frameless heatedwiper blade assembly of claim 18, wherein the outer layer and the innercore comprise first and second distinctly different materials.
 20. Theframeless heated wiper blade assembly of claim 8, wherein the elongatedbeam defines elongated opposite side edges and the electrical resistanceheater is disposed adjacent the opposite side edges of the beam.